1. Field of the Invention
The present invention relates to a medical device used for removing a membrane provided on an inner surface of a retina of an eye.
2. Discussion of the Related Art
Certain diseases involve the presence of a thin membrane of scar tissue that must be removed via a medical procedure. Examples of these procedures are the peeling of epiretinal membranes and possibly internal limiting membranes that are the result of idiopathic epiretinal membranes. These membranes may also be associated with macular holes and in vitreo macular traction syndrome, the peeling of epiretinal membranes in diabetic retinopathy, peeling of epiretinal membranes in proliferative vitreo retinopathy, peeling of epiretinal membranes after trauma, and the peeling of epiretinal membranes after intraocular inflammation, including uveitis and ophthalmitis.
Currently, these procedures are typically performed using one of three types of medical devices. Referring to FIG. 1(a), the first type is a sharp pick 1 comprising a needle 2, typically of size 20 to 23 gage, that is bent at one end. The bent end of the needle 2 forms a sharp point 3, which is used to engage the membrane 20. However, prior to using the sharp pick 1, a small incision often must be made in the membrane 20, as shown by the arrow in FIG. 1(a). Thereafter, the sharp pick 1 is inserted into the incision where the pick 1 is used to scrape along an edge of the incision between an inner surface of the retina 30 and a lower surface of the membrane 20 in an attempt to lift up the membrane 20 in a direction indicated by the arrows of FIG. 1(b).
However, the pick 1 has drawbacks. In particular, the pick 1 is able to engage a relatively small area of the membrane 20, making removal of all or large portions of the membrane 20 at the same time extremely problematic.
Referring to FIG. 2, the second medical device currently used to remove the membrane 20 is a pair of forceps 4, which are used to clamp a small portion of the membrane 20 along an outer edge or along an edge of an incision made therein. The forceps 4 grip the portion of the membrane 20 and lift the membrane 20 off of the retina 30. Because the forceps 4 engage such a small portion of the membrane 20, the forceps 4 have difficulty removing the membrane 20 in one piece and imparts the risk of leaving behind pieces of the membrane.
Referring to FIG. 3, the third medical device currently used to remove retinal membranes is a scraper 5, which commonly includes a piece of silicon tubing 6 with small pieces of diamonds 7 embedded onto an outer surface of the tubing 6. A region of the tubing 6 having the diamond pieces 7 embedded therein is applied to and scraped along an inner surface of the membrane 20, as indicated by the arrow in FIG. 3. The scraping action dislodges the membrane 20 from the surface of the retina 30. However, the scraping action requires downward pressure to be exerted on the retina 30, which creates a substantial risk of injury to the retina 30 and adjacent structures. Similarly, the scraper 6 is only able to engage a small area of the membrane 20, making removal of the membrane 20 in one piece very difficult and increasing the possibility of leaving pieces of the membrane behind. Finally, the scraper 6 necessitates the insertion of an additional instrument (not shown) into the eye to complete removal of the membrane 20 from the retina 30.
An additional drawback associated with each of the above devices, that is, the pick 1, the forceps 4, and the scraper 6, is that relatively high magnification levels must be used during the corresponding procedures for removing the membrane 20. The high magnification levels inherently decrease the area of the retina 30 that can be viewed by medical personnel when attempting to remove the membrane 20, thereby extending the time necessary to perform the procedure as well as making it more difficult for the medical personnel to successfully remove the membrane 20 in a single piece.